Engine silencer with transverse baffle structure



Nov. 27, 1951 F. H. KYFFIN 2,576,522

ENGINE SILENCER WITH TRANSVERSE BAFFLE STRUCTURE Filed Nov. 10, 1947 4 Sheets-Sheet l Nov. 27, 1951 2,576,522

ENGINE SILENCER WITH TRANSVERSEI BAFFLE STRUCTURE F. H. KYFFIN 4 Sheets-Sheet 2 Filed Nov. 10, 1947 u a I U m H? K r... I A :5 fa L 1 r r r W W AW 2 w F. H. KYFFIN Nov. 27, 1951 ENGINE SILENCER WITH TRANSVERSE BAFFLE STRUCTURE 4 Sheets-Sheet 3 Filed Nov. 10, 1947 Atlorney F. H. KYFFIN Nov. 27, 1951 ENGINE SILENCER WITH TRANSVERSE BAFFLE STRUCTURE 4 Sheets-Sheet 4 Filed Nov. 10, 1947 Attorney :ing. gas can'be cooled very rapidly "by ex-tractingits heat through the silencer walls which are in con Patented Nov. 27, 1951 UNITED STATES PATENT OFFICE ENGINE SILENGER WITH TRANSVERSE RAFFLE; STRUCTURE Frank'Hankinson Kyffin, Neston, .Wirral, England ApplicationiNovember 10,1947, Serial No. 785;101 In'Great'Britain December *28, 1946 1 Claim.

'- This invention is for improvementsiinlor relating to silencersior gases and-more particularly wengine and like silencers-such as are used in con- =1nection-withinternal combustion engines :of both the imotor-carand stationary type.

According to theepresent invention therelisprov-ideda silencer comprising a casing, at least wone longitudinally extending bafiie-orplate in the casing and at least one'transverselbafile the casing between the ends of the longitudinal-bathe, and apertures or gaps in'said bafiie arrangement and co operating therewith to -permit exhaust ;gases or the like to flow through or-round the baffles only or primarily in a direction around and along the casing and in contact with vor relatively close to the wall of the casing. Preferably, the exhaust gases are for-med or divided up-into astream orstreams of relatively small cross-sec- :l-tionalareaso that 'there is notv a thick body of gas passing through the si1encer,the.inner part of which thick body of gasis insulated to a large extent-from the heat extracting walls-of the eas- It will be appreciated that a thin stream of tactwith and are cooled by the atmosphere or by someuother cooling arrangement.

- In carrying the inventioniinto effect, the-utcause them to take a somewhatsinuous path.

Put another way, in :order: toreduce noise and "back pressure, the-exhaust gases arealternately compressed or baulked and then expanded and atthe same time'full useis made of the maximum area of the silencer outer casingfor cooling-purposes so as to reduce the volume of the gases. At

the same time the gases are sub-divided and caused to iiow at'least for a substantial distance in-longitudinal paths'or streams whilst also cirixculating around or'up and" down or from side to side and along the casing. "These separated streams of gas'intermingle again at least once during their passage throughthesilencer after which they'may be separated again but they in termingle before being finally discharged from the silencer so as not to issue from thefinal exhaustlpipe' in a-series of puffs butas a continuous stream.

Some specific embodiments of silencers according to the present invention willnow be described,

by way of example, with reference to the accompanying drawings, in which similar reference lnumeralslhave beenused inthe several embodiments to; indicate like parts. On the drawings: Figure 1 is a longitudinal sectional view of part of one embodiment of a silencer according to the present invention,

'Figure 2 .is a cross section: on the line AA of Figure .1,

V Figure 3 .is across section on the lineB B offFigure 1,

Figure 4 is a cross section on the line C0 of Figure 1,

Figure. 5 is afragmentary sectional view and shows a slight modification of the silencer shown in Figure 1,

, Figure 6 is a fragmentary sectional view and shows afurther slight modification of thesilencer shownlin Figure 1,

l Figure 7 .is a Across-section on the line J--J of Figure 6,

. Figure 8 (is a perspective view, with the outer casing partly broken away, of the .silencershown in Figures 1- to 4.

Figure 9 is a longitudinal sectional view of a further embodiment of theinvention,

Figure 10'isa cross-section on the lineD-D of Figure 9,

Figure 11 is a. cross-section on the line E-E of Figure 9,

Figure '12 is a longitudinalsectional view of a still further embodiment .of the invention,

:Figure l3 is across-section on'both the line F-Fand the line H--I-I- of Figure 12,

-Figure 14 is a cross-section on both the line GG and the line I-I of Figure 12,

- Figure 15 is a. longitudinal sectional view of v a still further embodiment of the invention,

Figure 16 isla cross-section on the line Y-Y of'Figure 15,

Figure 17 is a cross-sectionon the line XX of; Figure '15,

- Figure '18is a longitudinal sectional view of a still =further embodiment of the invention,

- Figure 19 is a cross-section onthe line XX of Figure 18,

-'Figure 20l-is across-section on the line YY ofv Figure 18, and

Figure 21. is adetail elevation of a modified Jform of transverse baffle plate to that adopted Ah the embodimentof the invention shown in Figures Land-8.

The embodimentof the inventionshownin Fig- ,ures 1 to. e-comprises a tubular casing [0 which is convenientl of-circular cross-section but may be square, oval or of other form. The endslof this tubular casing are closed by pairs of slight- 1y spaced endiplates ll, l2 and l3, M which are apertured and have welded to them respectively anlinlet p pe [5 .for'the exhaust gases and a discharge pipe I6 for saidgases after they have passed through "the silencer from the'inlet end chamber for the gases.

3 thereof to the outlet end. The exhaust inlet and outlet pipes may be centrally located or they may be arranged slightly out of centre with respect to the axis of the silencer casing, said pipes being, in the example shown in Figure 8, somewhat nearer the lower part of the casing.

Two longitudinally extending bafile plates H and I8 are located within the casing, these plates being spaced one above the other and having their edges l9 turned or flanged towards each other and spaced a slight distance from the walls of the casing as indicated at 2B. These baffle plates serve to divide the easing into three longitudinal compartments 2| 22 and 23, the upper and lower compartments; 2| and 23 respectively, being the smallest and being, of course, in the example shown, of segmental cross-section. The turnedin edges or flanges IQ of the plates above referred to may be of relatively shallow form so that the baffles are of tray-like construction or the flanged edges may be relatively deep as shown so that the flanges of one tray almost meet the flanges of the other. In all cases, however, there is a space 24 between the flange of one plate and the flange of the other. The flanges |9 may be flat and straight or inclined at an angle or they may be of curved form as shown, so as to conform to the curvature of the casing from which they are, of course, spaced. Some distance between the ends of the casing (e. g. midway) there is a transverse baflie 25 in the form of a disc having a central aperture 26 or alternatively, its opposite sides formed with rectangular notches or apertures 21, as shown in Figure 21. This transverse baflie serves to divide the foremost portions of the longitudinal passages 2|, 23 from the rearmost portions thereof. The ends of the longitudinal plates l1 and I8 terminate some distance short of the neighbouring end plates l2 and Mof the silencer casing and the space between said longitudinal plates at their ends is filled by end closure plates 28 and 29 welded, for example, to the end edges of the longitudinal plates. The closure plate 28 at the end of the silencer adjacent the inlet pipe I may be in the form of a humped deflector, as shown in Figure 5, the peak of the hump being in alignment with the axis of the inlet pipe.

The silencer above described operates as follows:

The exhaust gases enter the casing via the inlet pipe l5 and strike the end closure or deflector plate 28 just referred to. They are then distributed more or less evenly upwardly and downwardly and flow through the foremost longitudinal passages 2| and 23 between the longitudinal baflie plates and the casing. These passages are of relatively shallow segmental cross-section so that there are two streams of gases of relatively small volume flowing in intimate contact with the walls of the casing It! to which they rapidly lose heat and thereby volume. Some distance before they arrive midway along the length of the silencer the gases are baflled by the transverse baffle plate 25 and are caused to flow towards the axis of the silencer casing and into the foremost centre space 22 between the longitudinal plates H which space serves as a species of mixing It will be appreciated that the gases can pass into this space via the space 20 and the clearance 2a between the longiplates beyond the transverse baffle 25. From this space the gases again pass upwardly and downwardly around the longitudinal edges l9 of the longitudinal bafiie plates and into the rearmost upper and lower longitudinal passages 2| and 23 along which they flow in contact with the cooling walls of the silencer casing l0. Beyond the longitudinal baffle plates H and i8 the gases again intermingle to be discharged as a steady stream through the outlet pipe Hi. It will be noted that this embodiment of the invention makes good use of the outer casing of the silencer as a cooling means and the longitudinal baffles and transverse baffie cause the gases to flow in at least two streams along and around and with a somewhat sinuous motion from one end of the silencer to the other. This cooling effect on the gases as they flow through the compartments of the silencer efiectively reduces back pressure and noise. It has been found that the most efiicient results are obtained when the gases are divided so as to flow above the upper longitudinal plate and below the lower longitudinal plate in streams of substantially equal volume. It is believed that the space 22 between the'two longitudinal baffles serves as a mixing and expansion and/or compression chamber (1. e. there may be expansion at one point and compression at another). It is also to be noted that there are somewhat similar mixing and expansion chambers 30 and 3| adjacent the ends of the silencer casing.

In a further embodiment of the invention shown in Figures 9, 10 and 11, the silencer comprises a tubular casing ||l closed towards its ends by transverse plates l2 and I4. Longitudinal bafiie plates I! and is spaced some relatively small distance from the tubular casing extend between and are welded to said transverse end plates. There is also a further transverse plate 32 located, say, midway between the ends of the sliencer casing and extending between the two longitudinal baffle plates I! and I8. An inlet l5 for the exhaust gases, which may be centrally located or eccentric, is located in the end plate l2 so as to discharge into the foremost centre space 22 between the two baffle plates. The exhaust gases pass from this foremost centre space around the edges or flanges IQ of the longitudinal baffies and flow along the spaces 2| and 23 between these bafilles and the casing. Beyond the intermediate bafiie plate 32 the exhaust gases flow from the rearmost spaces 2| and 23 into the rearmost centre space 22 between the two longitudinal baffles and are discharged from the silencer through a discharge pipe |6 located similarly to the inlet pipe.

Although only a two compartment silencer has been described above, the silencer may, of course (see Figures l2, l3 and 14) consist of any number of chambers formed by increasing the number of transverse baffle plates 25 and providing one or more baffles 32 between the plates I1 and I8 and preferably by increasing the length of the silencer casing.

Figures l5, l6 and 17 show an embodiment of the invention in which there is only a single longitudinal baffle H8 at the foremost end of the silencer and a single longitudinal baiile H at the rearmost end. Transverse baffles 33 co-operate with the baffies H and E8 to constrain the gases to flow along and around the casing from the inlet to the outlet.

In a still further embodiment of the invention (see Figures 18, 19 and 20) an annular space or passageway 34 for the flow of the gases as a relatively thin skin, film or body in contact with the walls of the silencer casing, is formed by locating a tubular body 35 within the casing it! the walls of the tubular body being spaced from the Walls of the casing. Longitudinal apertures 36 and 31 and a transverse baffle co-operate to constrain the gases to flow along and around the space 34 somewhat after the manner described with reference to Figure 1 of the drawings. The end of the tubular inner body adjacent the inlet for the exhaust gases may be made conical or otherwise shaped to deflect the gases towards the wall of the casing. There may be longitudinal partition plates and/or transverse partition plates in said passage to divide the gases into several streams.

The spacing of the flanges Q9 of the longitudinal baiile plates from the casing may be as small as 1 1;" or even less. It is believed that the flanges 19 or equivalent device should be i as close as possible to the casing, the actual spacing depending on the cubic capacity of gases to be dealt with.

The longitudinal plates may be slotted, perforated, or pierced to assist the distribution of the gases. Furthermore, where a central or approximately central entry and/or exit pipe is not desired it may be advantageous to pass the gases along the foremost passages 2| and/or 23 first through the central chamber 22 and then along the rearmost passages 2| and/or 23.

The casing of the silencer can be of any shape and it may have a double or single skin and may be corrugated. In some cases a second skin is spaced from the inner skin to form a jacket through which a cooling medium may be passed. This cooling medium may be a current of cold air from the atmosphere induced to flow through the cooling jacket by the motion of the car and/or the use of a Venturi tube arrangement.

The interior or baffle structure may be preformed and be slid as a unit into the silencer casing. Bosses 33 (see Figures 6 and '7) may be punched up out of the flanges l9 and serve to locate and secure the inner baille structure in the outer casing. The inner structure may be secured to the casing by spot welding or the like or alternatively the flanges of the inner structure may be made slightly over size, and are inserted under pressure and after insertion spring out and exert pressure on the outer casing.

Satisfactory results have been obtained with the sides of the space between the upper and lower longitudinal plates open, but it is generally found advantageous to close this space partially by the flanges l9 formed on or welded to the side edges of the longitudinal plates.

The parts of the silencers above described lend themselves to a construction on mass production lines.

The tubular body part or casing of the silencer may be of double or multi-skin form, e. g. it may comprise several concentric tubes fitted snugly one into the other.

There may, of course, be more than two spaced apart longitudinal plates in the deflector means. Furthermore, the chambers formed by the deflector means may differ in size as regards their length and/or cross-section.

It will be appreciated that the silencer may be fitted with the longitudinal plates in a horizontal, vertical or inclined plane.

The silencer according to the present invention can be applied to various purposes for which a silencer is required. One particular further application which may be mentioned is to the air intake of an internal combustion engine, compressor or the like.

The transverse baflle herein referred to may, of course, also be an end-plate of the silencer.

I claim:

A silencer for exhaust gases comprising two tubular members located one within the other to define an elongated annular space therebetween and of small thickness relative to the diameter of the inner tubular member, a transverse bafile at each end and intermediate the ends of the silencer, at least one of said transverse bafiies closing the inner tubular member and at least one of said transverse baiiles closing the annular space, inlet means for exhaust gases at one end of the silencer, and outlet means for exhaust gases at the other end of the silencer, the inner tubular member being formed by two oppositely disposed plates having their longitudinal side portions curved inwardly towards but terminating short of one another so as to define small aperture means in the side walls of the inner tubular member, whereby exhaust gases are caused to flow primarily around and along the annular space.

FRANK HANKINSON KYFFIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,173,583 Johnston Feb. 29, 1916 1,972,065 Noblitt Aug. 28, 1934 2,150,768 Hedrick Mar. 14, 1939 2,189,424 Leadbetter Feb. 6, 1940 2,225,650 McCurdy Dec. 24, 1940 FOREIGN PATENTS Number Country Date 507,463 Great Britain June 15, 1939 

